1. Field of the Invention
The present invention relates to an expandable vinyl chloride resin composition suitable for application as an interior material for automobiles or as a material for bags, and a crosslinked expanded product obtained from such a composition.
2. Discussion of Background
Inventions relating to crosslinkable highly expandable vinyl chloride resin compositions have been known as disclosed, for example, in Japanese Examined Patent Publications No. 16498/1977 and No. 44588/1977. However, crosslinking agents such as diisocyanates as disclosed in these inventions have their functional groups not blocked and have a drawback that they readily react with moisture or with other functional groups to loose the crosslinking properties as time passes during the storage of the compositions even at a low temperature. Therefore, such compositions are required to be molded immediately after the preparation, and it is difficult to store them for a long period of time or to mold them at an optional time. Even if the molding can be conducted, it is difficult to adjust the crosslinking and foaming speeds, and with the compositions which have been stored, the crosslinking reaction tends to be inadequate, and it has been difficult to constantly produce a highly expanded molded product. Further, these compositions have a drawback that for their molding, it is necessary to adopt a heating system of two steps of gelation (crosslinking) and foaming, and the process tends to be cumbersome.